Learn Italian: Eravate meno timidi di noi. - You all were less shy than us.

The imperfetto is used to describe continuous states, characteristics, or ongoing situations in the past. Since being shy is a past state or personality trait rather than a single completed action, we use eravate (you all were) instead of the passato prossimo.

Why does the sentence use di to mean "than" instead of che?

When comparing two pronouns or nouns (like the implied voi and noi) using a single adjective (timidi), Italian uses di for "than". You would generally use che if you were comparing two different adjectives about the same subject (like "more shy than angry").

Why does timidi end in an "i"?

Adjectives must agree with the subject they describe. Eravate is the "you all" form of the verb, implying the plural subject voi. Therefore, the adjective timido changes to the plural masculine timidi. If the group you were talking to was entirely female, it would be timide.

Can I say Voi eravate instead of just Eravate?

Yes, but it is not necessary. Because the verb form eravate only ever goes with voi (you all), the pronoun is usually dropped. You would only add Voi for strong emphasis, like "YOU ALL were less shy than us."